Climate change warning: Greenland once melted and raised the ocean 5 feet.

“There’s a boy here, of course.” It was my first day. I’d been hired to help with the holiday-season rush at a small historic house museum located in a tiny nature preserve tucked alongside a Toronto expressway. That morning, as the city was hushed by the year’s first snowfall, I took the subway and a bus and then walked down a steep hill, half slipping on the slick pavement. I arrived, eventually, at Todmorden Mills Heritage Museum and Arts Centre, home to a weathered nineteenth-century brewery, a paper mill, and two small historic houses, one yellow and one grey. “A boy? Like ....